Field of Invention
This invention relates to a roll housing on an agricultural machine. More specifically, it relates to a compression roll housing on a harvesting machine, for example, a forage harvester.
Description of Related Art
A forage harvester has a front attachment which includes a front cutter and a mechanism for feeding the cut crop to compression rolls where it is compressed. The compressed crop is then cut by cutters before being fed into a discharge chute.
The compression rolls which comprise a drum and a shaft are contained within a compression roll housing. Typically, three sets of rollers are arranged in pairs, each set having an upper and lower roller so that the crop is fed and compressed between each set. The housing comprises apertures so that the rolls can be mounted within the housing with the shafts protruding through the apertures. The rollers must be mounted so that the distance between the upper and lower rolls can be altered in order to facilitate cleaning and repairs and to allow the compression thickness to be altered. Typically, the shafts of the upper set of rollers are mounted within longitudinal apertures which extend generally vertically on the sides of the housing. This means that when the shaft is secured at a desired height within an aperture, there is at least one portion of the aperture which is not filled by the shaft though which harvested material in the housing may escape which in turn reduces the yield of compressed, cut crop and can cause damage/blocking to other parts of the machine. The movements of the upper rolls are achieved through the crop material which flows through them.
EP 0541 975 B1 discloses the use of sliders to seal, or cover roll housing apertures. The sliders are mounted within guides provided on the housing and are pivotally connected so that the sliders are vertically moveable over the aperture when there is movement of the shaft within the aperture.
Such sliders tend to cant which restricts movement. EP 0 541 975 B1 tries to overcome this problem by fitting the sliders into guides to avoid canting. Even if canting during movement is avoided by reducing the slackness between the guides and sliders, the uncovered guides are likely to be soiled by dust or crop from the housing which may restrict movement of the sliders. Further, when the slider is in an upper position a part of the aperture below is not covered by the slider because the length of the slider is limited due to the proximity of the shaft of a lower roll.